1. Field of the Invention
The present invention relates to a control system and a timing rotor for a multi-cylinder internal combustion engine.
2. Description of Related Art
For example, Japanese Patent Number 3076556B2 recites a two cylinder V-type internal combustion engine, in which an angular interval between a top dead center of one of two cylinders and a top dead center of the other one of the two cylinders is set to be 60° CA. This internal combustion engine has a timing rotor, which is provided to sense a rotational angle at the time of outputting the force from the engine. The timing rotor has two teeth, which are spaced from each other by an amount that corresponds to an angular interval between the top dead center of the one cylinder and the top dead center of the other cylinder. When a corresponding one of these teeth is sensed by a rotational angle sensor, an ignition pulse signal of the corresponding cylinder is generated.
Recently, even for this type of multi-cylinder internal combustion engine, it has been demanded to more accurately set ignition timing, fuel injection start timing and a fuel injection period. However, when the above timing rotor is used, the ignition timing needs to be set based on an average required time period, which is required for the timing rotor to make one full rotation, and an average rotational speed of the timing rotor during the one rotation. It is difficult to perform this with high accuracy.
Here, it is conceivable to use a timing rotor that has multiple teeth arranged at equal angular intervals, each of which is a quotient of a full rotational angle of the timing rotor divided by an integer number. However, in such a case, when the above internal combustion engine is one, in which an angular interval between the piston top dead center of the one cylinder and the closest one of the piston top dead center and the piston bottom dead center of the other cylinder is not a quotient of the full rotational angle of the output shaft, the ignition timing cannot be set with high accuracy. For example, this is a case where the above angular interval of the teeth is set to be 55° CA, which is not a quotient of the full rotational angle of the output shaft. This is due to the fact that the interval between the piston top dead center and the corresponding tooth varies from one cylinder to another cylinder.